Spring sash balance



Feb. 17, 1959 E. E. FOSTER SPRING SASH BALANCE Filed June 5, 1955 INVENTOR Edm'n E. Faster BYW, W

ATTORNEY? United States Pate r SPRING SASH BALANCE Edwin E. Foster, Austin, Tex. Application June 3, 1955, Serial No. 513,087 4 Claims. (Cl. 16-197) This invention relates to spring counterbalances for windows of the type shown in U. S. Patent No. 2,609,193 issued September 2, 1952.

It is an object of this invention to provide a constant tension spring with a guide member to act as a reaction bar or plate during the up and down movement of the window. A further object of the invention resides in the provision of means as a reaction member to eliminate variables due to the slacking of a spring ribbon coil which causes a change of leverage to result in non-uniform counterbalance forces.

An important object of the invention is to provide a spring counterbalance for windows including an adjustable balance using the friction factor to add to the strength of the spring. This friction factor is provided having the spring uncoil with wrap-around action by threading the spring through a specific slot in the guide member depending upon the counterbalance weight desired.

Further objects will be apparent from the following description when considered in connection with the accompanying drawing in which:

Fig. 1 is a side View partly in section of a guide member,

Fig. 2 is a view similar to Fig. 1 adjusted in another position,

Fig. 3 is a side elevation of the guide member,

Fig. 4 is a vertical sectional view of the guide member, and

Fig. 5 is a cross section of a detail.

The metal stamping 77 is provided with screw holes 78 which fasten the mounting into the pocket of the window sash. Onto this mounting base 77 is attached a stamped cup member 79 which is provided with a slot 80, through which the self-coiling spring extends. The rim of the cup 79 is provided with teeth or notches which correspond to notches in a circular ring stamped into the base 77. A screw 81 holds the cup 79 against the mounting 77 and prevents the cup from rotating when the load comes against it, due to the tension of the self-coiling spring. The bottom of the cup is marked with numbers, Fig. 3, which correspond to the weight supported when the cup is adjusted to the diiferent positions. For instance, when the slot is in the position shown in Fig. 1 none of the wrap-around friction is added, so that the balance carries only the five pounds by the spring tension. When the cup is moved to the position shown in Fig. 2, the added wrap-around friction causes the balance to support 7 pounds. In the position marked 8, the additional wraparound action causes it to support 8 pounds. By moving the cup still farther counterclockwise to the position marked 10, Fig. 3, the sash balance will support 10 pounds. The clamping screw is then tightened to lock the cup through the engaging teeth to stay in the position selected.

The advantage of having an adjustable sash balance of this type is that it eliminates the large inventory required to take care of the various weight sashes when the straight self-coiling spring in a regular housing is used.

I claim as my invention:

1. A sash balance comprising a pre-stressed, tightly wound and self-coiling spring, a mounting base, a cupshaped member having a slot mounted on the base, said coiled spring being mounted in the cup-shaped member and projecting out through the slot, and means secured to the base and the cup-shaped member to adjust the latter to a desired position relative to the slot, said spring coiling and uncoiling in the cup-shaped member to provide a constant counterbalance force for the window.

2. A sash balance according to claim 1, in which said means is a screw member secured to the base, and the cup-shaped member to adjust the latter to adesired position of the slot, said spring coiling and uncoiling in the cup-shaped member to provide a constant counterbalance force for the window.

3. A sash balance according to claim 1, in which said cup-shaped member has indicating means thereon as a guide for adjustment of the cup-shaped member to a certain indication dependent on the weight to be counterbalanced.

4. A sash balance according to claim 1, in which said cup-shaped member has a plurality of teeth in contact with the base to prevent relative movement between them when in adjusted position.

References Cited in the file of this patent UNITED STATES PATENTS 149,940 McKay Apr. 21, 1874 1,019,690 Odermatt Mar. 5, 1912 2,609,193 Foster Sept. 2, 1952 2,635,282 Trammell et a1. Apr. 21, 1953 2,684,499 Lewis July 27, 1954 2,739,344 Dickinson Mar. 27, 1956 OTHER REFERENCES The Ironmonger, page 139, October 27, 1888. 

